In 1989, Lynn began wrestling for Verne Gagne's American Wrestling Association, where by the end of 1990, he became the last challenger for the AWA World Heavyweight Championship, held by Larry Zbyszko.
Lynn first joined the World Wrestling Federation in May 1989 as enhancement talent, losing to Rick Martel, and teaming with Ray Brown in a loss to Big Boss Man and Akeem later that night. In April 1995, Lynn returned in a singles loss to Rad Radford and teamed up with Lenny Lane in a loss to The Heavenly Bodies the next night. In August 1997, Lynn defeated Steve Casey, but lost to Taka Michinoku later that night.
In September 1995, Lynn joined World Championship Wrestling, alternating between wrestling under his real name and under the masked alter-ego Mr. J.L.. He joined WCW's cruiserweight division, where he competed against a variety of wrestlers from around the world such as Chris Benoit, Dean Malenko, Eddie Guerrero, Sabu, Chris Jericho and Alex Wright. Lynn suffered a broken arm on December 18, 1995, in a match against Dean Malenko that would air one week later on Nitro on Christmas night.
One of his last major matches took place at the Clash of the Champions XXXV, where he suffered a six-man tag team loss while teaming with Konnan and La Parka against Chris Jericho, Super Calo and Chavo Guerrero, Jr.. While he was injured, Eric Bischoff fired him from WCW in July 1997.
After leaving WCW, Lynn joined Extreme Championship Wrestling (ECW), where he debuted as a fan favorite at As Good as it Gets event at the ECW Arena on September 20, 1997, and immediately began a "respect" feud with Justin Credible, who debuted against Lynn that same evening. Lynn formed a team with Tommy Rogers as the two began a rivalry with the team of Chris Candido and Lance Storm, losing to them in a match at Ultimate Jeopardy. Lynn made his pay-per-view debut in ECW at November to Remember, where he rescued Rogers from a double-team assault by Candido and Storm, leading to an immediate rematch between the two teams, which Rogers and Lynn lost again. Lynn defeated Chris Candido at the 1998 House Party. He then formed a tag team with Chris Chetti to feud with The Full Blooded Italians (Little Guido and Tracy Smothers), whom Lynn and Chetti defeated in matches at Hostile City Showdown and Living Dangerously.
Lynn was next booked in a series of matches against his fellow debutant Justin Credible, which saw Credible winning the last match in the feud at the Heat Wave pay-per-view. After this, Lynn was involved in a feud with Lance Storm and Mikey Whipwreck, a feud that was shortened when Whipwreck left for WCW.
Once the feud with Lance Storm ended, Lynn was booked in a match for the ECW World Television Championship with Rob Van Dam at Living Dangerously in 1999. The finish saw Lynn win the title from Van Dam (the time limit expired and Lynn was awarded the title by referee decision instead of by pinfall or submission). Despite this win, he asked for a five-minute time extension, in which he was pinned by Van Dam after a Five-Star Frog splash. Though Lynn did not win the match, he from then on referred to himself as "The New F'N Show", mocking Van Dam's nickname, "The Whole F'N Show", as well as claiming he would be the wrestler to deprive Van Dam of the title. Though Lynn received several more title opportunities with Van Dam, he was not successful in winning the World Television Title before Van Dam was stripped of the title after suffering a legitimate broken ankle. Around the same time, Lynn also suffered a broken ankle, taking him out of action. On his return to ECW television, Lynn challenged Van Dam to one more match at Hardcore Heaven, which Lynn won due to interference by Scotty Anton.
On October 1, 2000 at Anarchy Rulz, Lynn defeated Justin Credible for the ECW World Heavyweight Championship. He held the title for one month, making a successful title defense against Steve Corino, to whom he lost the title to in a rematch. At the last ECW pay-per-view, Guilty as Charged in 2001, Lynn was in the main event, losing to Rob Van Dam via a Van Terminator.
Following the bankruptcy of ECW in April 2001, Lynn was hired by the WWF. Lynn made his television debut on the April 29, 2001 episode of Sunday Night Heat, where he defeated Crash Holly for the Light Heavyweight Championship in his debut match. He would hold the championship for 37 days and would successfully retain over former champions Crash Holly, Taka Michinoku, Dean Malenko and Essa Rios, as well as Christopher Daniels, Grandmaster Sexay and others. He eventually lost the title to Jeff Hardy and had a notable match with Rob Van Dam for the WWF Hardcore Championship on an episode of Sunday Night Heat before being released in February 2002, following a knee injury.